openSenseMap
Data from Personal Weather Stations called senseBoxes
Real-time UV Index Forecast.
OpenUV API is a free Weather API that requires apiKey authentication, is served over HTTPS and has unconfirmed CORS support.
The missing minimalistic JSON real-time UV Index API for awesome Developers, Innovators and Smart Home Enthusiasts you've been looking for.
Details from openuv.io.

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Data from Personal Weather Stations called senseBoxes
The OpenUV API is provided by OpenUV (openuv.io). The missing minimalistic JSON real-time UV Index API for awesome Developers, Innovators and Smart Home Enthusiasts you've been looking for.
Yes. The OpenUV API is listed in the Weather category of the public-apis directory, which only includes APIs that are free or have a free tier. Check its documentation for rate limits and paid plans.
Yes. The OpenUV API uses apiKey authentication, so you need to register for credentials before making requests.
CORS support for the OpenUV API is unknown. Test a request from the browser, and fall back to a server-side call if it is blocked.
Yes. The OpenUV API is served over HTTPS, so it's safe to use in production.